Powered boat hull

ABSTRACT

A hydrofoil craft, particularly a method of economically modifying a conventional hull with cambered foils to obtain and calculate increased lift from dense spray and to achieve enhanced craft performance is disclosed. The present invention improves speed, fuel efficiency and rough water stability, reduced pitch and vertical accelerations. A catamaran or V-bottom hull ( 20 ) is modified with chine mounted aerofoils ( 32, 33, 28, 28 A), flexible dihedral cambered foils positioned beneath the water line and on either side of the bow ( 30, 31 ) so as to create turbulence in the forward end of a tunnel(s) ( 26 ). Fixed forward tunnel cambered foil(s) ( 28 ) and/or fixed or adjustable center tunnel cambered foils at the stern ( 28 A) end of the tunnel ( 26 ) to generate lift from pressure caused by dense spray in the tunnel(s) ( 26 ) may also be provided.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This nonprovisional application claims priority under 35 U.S.C. §119(e) on U.S. Provisional Application No. 60,274,665, entitled PoweredBoat Hull, and filed on Mar. 12, 2001, the entirety of which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is related to waterborne craft, and moreparticularly to the use of flexible adjustable cambered foils to obtaina very high ratio of speed to horsepower by enhancing lift, performanceand stability in rough water in a hydrofoil craft. The present inventionis particularly applicable to all types of watercraft including, but notlimited to v-bottom and catamaran boat hulls incorporating hydrofoils.

[0004] 2. Description of the Background Art

[0005] A conventional, modified boat hull and method of modifying theboat hull have been described in U.S. Pat. Nos. 4,896,621 and 4,951,591to Coles, the entirety of each of which is hereby incorporated byreference. The inventions of Coles have been described to obtainenhanced lift and rough water stability for vessels.

[0006] The method includes defining or modifying with chine aerofoilskirts an axial tunnel(s) intermediate the bow and transom of the boathull, positioning flexible dihedral foils below the water line and onthe bow so as to obstruct and create turbulence in the forward end ofthe tunnel while cushioning and lifting the bow. Simultaneously, thetransom end of the tunnel is enclosed with stern foils so as to compresssaid turbulence and thereby lift the transom.

[0007] The following references generally describe the related art andare related to the aforementioned technology, specifically U.S. Pat. No.2,989,279 (Le Bel); U.S. Pat. No. 3,763,811(Danahy); U.S. Pat. No.3,117,545 (Warner); U.S. Pat. No. 4,237,810 (Westfall); U.S. Pat. No.3,117,347 (Cohen et al.); U.S. Pat. No. 4,523,526(Smoot); U.S. Pat. No.3,131,436 (Lathers et al.); U.S. Pat. No. 4,606,291 Hoppe; U.S. Pat. No.3,221,697 (Allegretti); U.S. Pat. No. 4,649,851 (April); U.S. Pat. No.3,357,390 (Wray); U.S. Pat. No. 4,665,853 (Gerdsen et al.); U.S. Pat.No. 3,372,663 (Lo Bue); U.S. Pat. No. 4,715,304 (Steinberg); U.S. Pat.No. 3,424,120 (Koriagin); U.S. Pat. No. 4,496,621 (Coles); U.S. Pat. No.3,477,400 (Walker); U.S. Pat. No. 4,951,591(Coles); and U.S. Pat. No.3,604,384 (Coles). Foreign Patent Documents 477050(Australia), 124594(New Zealand), and 1421624 (France) are also related to the backgroundof the invention.

[0008] The present inventor has discovered that there are numerousshortcomings with the related art that, as overcome by the presentinvention, will result in superior vessel design to obtain a very highratio of speed to horsepower by enhancing lift, performance andstability in rough water, particularly with respect to a hydrofoilcraft.

SUMMARY OF THE INVENTION

[0009] The present invention overcomes the shortcomings associated withthe background art and achieves other advantages not realized by thebackground art.

[0010] An aspect of the invention is to provide a method of modifyingand designing a boat hull to obtain and calculate enhanced lift,performance and rough water stability. The method to obtain enhancedperformance includes defining or modifying with chine aerofoil skirtsand axial tunnels intermediate the bow and transom of the boat hull,positioning flexible dihedral cambered foils below the waterline and onthe bow so as to create a turbulence in the forward end of the tunnel.This turbulence mixes water and air to generate a dense spray that liftsthe bow while cushioning shock. The method may also include positioningfixed or adjustable cambered foils at the stern end of the tunnel togenerate lift from the dense spray in the tunnels. Alternatively, or inconjunction with the other foil arrangements, the method may includeenclosing the transom end of the tunnels with a rigid adjustablecambered airtight foil to compress dense spray, lift the transom anddampen pitch to prevent the bow from diving in a rough sea.

[0011] The aforementioned method is particularly advantageous increating a hydrofoil system for a modified hull in order to obtainexcellent stability and performance at high speeds in rough water as aresult of substantial lift. The present invention creates hydrodynamiclift from the twin swept back surface piercing flexible forward camberedhydrofoils. Hydrodynamic lift from tunnel(s) on a catamaran hull or a Vbottom hull modified with chine-mounted aerofoils, tunnel mountedcambered foils and/or stern cambered foils is also created bycompressing the flow of dense spray at a high velocity with the camberedtunnel(s) and stern foil(s). Lift is created in the tunnel camberedfoil(s), on the chine mounted aerofoils and stern cambered foils fromthe high velocity, dense spray when the transom end of the tunnels isrestricted by the stern cambered foil(s).

[0012] Another aspect of the present invention includes a method forcalculating the amount of enhancement of performance from modifying theboat with the cambered bow, tunnel and stern foils, comprising (a)defining before modification the boat height above water, trim, wettedsurface, drag and weight vs horsepower and speed; (b) definingmodifications of bow, forward, center and stern cambered foils; (c)defining cambered foil lift; (d) defining cambered foil drag; (e)defining after modification of cambered foils hull lift; (g) definingspeed vs horsepower before and after modification.

[0013] The substantial lift generated by the dense spray and the foilsystem of the present invention reduces the rough water wave profileimpacted by the hull, so as to reduce the wave shock and improve hullstability and performance at high speeds. Accordingly, the presentinvention reduces power requirements and hull structural strength andweight minimum requirements.

[0014] Another aspect of the present invention is the implementation ofa watercraft trim control system that effectively and safely contributesto craft operation. Trim changes of the engine shaft change the angle ofattack of the bow cambered foils and raise or lower the bow. Raising orlowering the rigid airtight cambered stern foils raises or lowers thestem. Trim control of the hull is essential to reduce the danger ofpitching up or down at high speeds in a rough sea.

[0015] An additional aspect of the present invention is directed towarda hydrofoil craft, particularly a method of economically modifying aconventional hull with cambered foils to obtain and calculate increasedlift from dense spray and enhanced performance. The present inventionimproves speed, fuel efficiency and rough water stability, reduced pitchand vertical accelerations. The method of obtaining enhanced performanceis characterized by defining an axial tunnel(s) intermediate the bow andtransom of a catamaran hull or a V-bottom hull modified with chinemounted aerofoils; positioning flexible dihedral cambered foils beneaththe water line and on either side of the bow so as to create aturbulence in the forward end of the tunnel that mixes water and air togenerate a dense spray that lifts the bow while cushioning shock. Fixedforward tunnel cambered foil(s) and/or fixed or adjustable center tunnelcambered foils positioned at the stem end of the tunnel to generate liftfrom pressure caused by dense spray in the tunnel(s) are also includedin the present invention. The present invention may also includesimultaneously or alternatively enclosing the transom end of thetunnel(s) with a rigid adjustable, vertically and or in angle of attack,cambered foils to compress the dense spray and lift the transom.

[0016] These and other aspects of the invention are specificallyaccomplished by a boat hull comprising a bow and a stern; a waterlineextending between the bow and the stern; at least one tunnel extendingaxially in a direction from the bow toward the stern and having aforward end, a center region and an aft end; a pair of flexible camberedfoils, the flexible cambered foils supported on sides of the bow beneaththe water line, the flexible cambered foils being capable of controllinga flow within the at least one tunnel and creating a dense spray in anend of the tunnel while cushioning shock and lifting the bow; and atleast one fixed, cambered foil at the after or the forward end of the atleast one tunnel generating lift from a pressure being generated by thedense spray within the at least one tunnel.

[0017] These and other aspects of the invention are also accomplished bya boat hull comprising a bow and a stern, the stern including a transom;a waterline extending between the bow and the stern; a pair of tunnelsextending axially in a direction from the bow toward the stern andhaving a forward end, a center region and an aft end; a pair of flexiblecambered foils, the flexible cambered foils supported on sides of thebow beneath the water line, the flexible cambered foils being capable ofcontrolling a flow within the at least one tunnel and creating a densespray in an end of the tunnel while cushioning shock and lifting thebow; and at least one pair of cambered tunnel foils at the after orforward ends of the tunnels, respectively, wherein each of the tunnelsincludes a respective tunnel foil generating lift from a pressure beinggenerated by the dense spray within the at least one tunnel.

[0018] Further scope of applicability of the present invention willbecome apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will become more fully understood from thedetailed description given hereinafter and the accompanying drawingswhich are given by way of illustration only, and thus are not intendedto limit the present invention to the embodiments shown, and wherein:

[0020]FIG. 1 is a side perspective view of a catamaran hull modifiedaccording to an embodiment of the present invention;

[0021]FIG. 2 is a rear elevation view of the catamaran hull of FIG. 1;

[0022]FIG. 3 is a front elevation view of the catamaran hull of FIG. 1;

[0023]FIG. 4 is a partial, exploded, front sectional view, showing thefitting of twin flexible cambered foils adjacent to a bow of a boataccording to the present invention;

[0024]FIG. 5 is a fragmentary rear elevation view showing a sterncambered foil, rigid hovercraft type skirt according to an embodiment ofthe present invention;

[0025]FIG. 6 is a fragmentary side elevation view showing a rigidadjustable cambered foil hovercraft type skirt;

[0026]FIG. 7 is a fragmentary side elevation view showing a tunnel witha center adjustable cambered foil and a rigid adjustable, cambered sternfoil having a forward end in the tunnel according to an embodiment ofthe present invention;

[0027]FIG. 8 is a fragmentary side elevation view showing a tunnel witha forward, fixed cambered foil, a tunnel center adjustable camberedfoil, and a rigid adjustable cambered stern foil;

[0028]FIG. 9 is a rear elevation view of a twin tunnel hull constructionhaving a single rear engine according to an embodiment of the presentinvention;

[0029]FIG. 10 is a rear elevation view of a twin tunnel hullconstruction having a duel rear engine according to an embodiment of thepresent invention;

[0030]FIG. 11 is a rear elevation view of a modified twin tunnelconstruction having a single rear engine according to an embodiment ofthe present invention;

[0031]FIG. 12 is a rear elevation view of a hull having a single tunnelwith twin engines according to an embodiment of the present invention;

[0032]FIG. 13 is a partial, side elevation view, partially in phantom ofthe catamaran hull of FIG. 1 having pairs of bow, forward and centertunnel, and stern cambered foils according to an embodiment of thepresent invention;

[0033]FIG. 14 is a fragmentary sectional view showing the fitting ofcambered foils adjacent the bow, forward in the tunnel, aft in thetunnel and at the stern in a position intersecting the tunnel accordingto an embodiment of the present invention;

[0034]FIG. 15 is a longitudinal sectional view of the boat hull of thepresent invention shown in FIG. 13 underway at relatively low speeds;

[0035]FIG. 16 is a longitudinal sectional view showing the boat hull ofthe present invention shown in FIG. 13 underway at high speed with astern foil closed so as to compress the dense spray within a tunnel;

[0036]FIG. 17 is the rear elevation view of the boat shown in FIG. 16;

[0037]FIG. 18 is a schematic exploded view of the boat shown in FIGS.13, 15 and 16, and having the pairs of bow foils, forward tunnel foils,center tunnel foils and stem foils;

[0038]FIG. 19 is a fragmentary side elevation view of a flexiblecambered bow foil according to an embodiment of the present invention;

[0039]FIG. 20 is a bottom plan view of the cambered foil shown in FIG.19;

[0040]FIG. 21 is a fragmentary end elevation view of an embodimenthaving a bow foil positioned on a V-bottom boat hull;

[0041]FIG. 22 is a schematic view of the of shims or hydraulic means toadjust the angle of attack (x) of a cambered bow foil according to thepresent invention;

[0042]FIG. 23 is a side elevation view of a twin tunnel hull having bowcambered foils, forward tunnel cambered foils, center tunnel camberedfoils and a pair of stern cambered foils according to an embodiment ofthe present invention;

[0043]FIG. 24 is a plan view of the hull shown in FIG. 23;

[0044]FIG. 25 is a side elevation view of a V-bottom or rigid inflatablehull modified with a chine aerofoil skirt to define axial tunnelsinfluenced by the cambered bow foils, cambered center tunnel foils andcambered adjustable stern foils;

[0045]FIG. 26 is a rear elevation view of the V-bottom hull shown inFIG. 25;

[0046]FIG. 27 is a plan view of the V-bottom hull shown in FIG. 25;

[0047]FIG. 28 is a partial, side elevation view of the V-bottom hullshown in FIG. 25, demonstrating compression of tunnel turbulence anddense spray by stem foils.

[0048]FIG. 29 is a rear view of the boat hull shown in FIG. 23; and

[0049]FIG. 30 is a side view according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] The present invention will hereinafter be described withreference to the accompanying drawings. Hereinafter, the presentinvention will be described in detail with reference to the accompanyingdrawings. The present invention is an improvement over previouswaterborne craft hulls available in the related art. The details andarrangements found in U.S. Pat. No. 4,896,621, U.S. Pat. No. 4,951,591,and U.S. Pat. No. 3,604,384 all to the inventor of the present inventionColes, are hereby incorporated in their entirety by reference into thepresent application.

[0051] Although the present invention is directed toward any waterbornecraft, boat, ship or other type of vessel, the following descriptionwill employ the use of the terms boat and hull for simplicity. Inaddition, one of ordinary skill in the art will appreciate that thefollowing description relies upon terms generally understood in therelated art, including but not limited to forward, stem, bow, stem,transom, camber, lift, starboard, port and waterline(s). One of ordinaryskill in the art will appreciate that a waterline is typically the lineof the water's edge when a waterborne craft is afloat, technically theintersection of any horizontal plane with the molded form of the ship.In practice, the designer anticipates the preferred operation of thevessel and the positioning of the waterline based upon vessel dimension,loading sea state, etc.

[0052] The present invention is particularly suited to a catamaran typeof hull readily fabricated from metal or molded plastic material andmodified to include a tunnel(s) defined between two hull sections orpontoons. Alternatively, the present invention is equally applicable toa V-bottom type of hull having pairs of cambered foils fore-and-aftadapted to be acted upon both by a water stream and a dense spray inorder to assist in lifting the hull when the boat is under power. One ofskill in the art will appreciate that variations and/or combinationsincluding features of both V-bottom and catamaran hulls are anticipatedby the present invention.

[0053] As aforementioned, the bow foils on the bow of a boat may beformed as surface piercing cambered hydrofoils and shaped so that theycooperate in creating turbulence, e.g., in the form of a dense spray ina flow stream passing thru the tunnel(s) while assisting in increasingthe lift of the hull which is largely out of the water when the boat istraveling at a relatively high speed. A highly desirable combination oflift and stability may be provided by various combinations of bowsurface piercing cambered hydrofoil(s), forward fixed tunnel camberedfoil(s) and/or center fixed or adjustable tunnel cambered foil(s) andadjustable, rigid, airtight, cambered foil(s) applied to a hovercraftskirt or hull. A catamaran hull embodiment and a v-bottom hull or rigidinflatable hull embodiment of the present invention will be describedhereinafter in greater detail with reference to the accompanyingdrawings.

Catamaran Hull Embodiment

[0054]FIG. 1 is a side perspective view of a catamaran hull modifiedaccording to an embodiment of the present invention. FIG. 2 is a rearelevation view of the catamaran hull of FIG. 1. FIG. 3 is a frontelevation view of the catamaran hull of FIG. 1. FIG. 4 is a partial,exploded, front sectional view, showing the fitting of twin flexiblecambered foils adjacent to a bow of a boat according to the presentinvention. FIG. 5 is a fragmentary rear elevation view showing a sterncambered foil, rigid hovercraft type skirt according to an embodiment ofthe present invention. FIG. 6 is a fragmentary side elevation viewshowing a rigid adjustable cambered foil hovercraft type skirt. FIG. 7is a fragmentary side elevation view showing a tunnel with a centeradjustable cambered foil and a rigid adjustable, cambered stern foilhaving a forward end in the tunnel according to an embodiment of thepresent invention. FIG. 8 is a fragmentary side elevation view showing atunnel with a forward, fixed cambered foil, a tunnel center adjustablecambered foil, and a rigid adjustable cambered stern foil, wherein thecenter and stern foils may be adjusted by a hydraulic jack and trimplate mounted on a vessel transom.

[0055]FIGS. 1, 2, 3 and 13 show a catamaran hull 20 having integral portand starboard pontoons 23, 24, respectively. The hull 20 may befabricated or molded intergrally of a plastic material conventionallyknown in the related art for boat hulls, such as polyurethane and/or itsequivalents. Regardless of the mode of construction, the pontoons 22 and24 form between them an axial tunnel 26. The axial tunnel 26 may includefixed or adjustable cambered center foils 28, cooperatively associatedwith pairs of bow flexible cambered foils 30, 31, and a pair ofadjustable, rigid, cambered stern foils 32, 33. The form, function andmode of operation of the bow foils 30, 31, center foils 28 and sternfoils 32, 33 are explained in greater detail hereinafter.

[0056] The hull 20 may include an open cockpit 34, furnished with awindshield 36. At the rear of the cockpit 34, a transom 38 for closingthe cockpit 34 and reinforced to support an outboard motor 39 and/oralternatively an inboard, outboard drive or jet drive of reasonablysmall power for speeds which are obtained in rough water is alsoprovided. As shown in all views, bow port 30 and bow starboard camberedfoils 310, 31 are separately attached, e.g. with bolts, to exteriorpontoon surfaces.

[0057] Similarly forward and center tunnel cambered foils 28, 28A, andaft port 32 and aft starboard cambered foils 33 are individually securedto the hull in similar manners. As shown in FIG. 4, a preferredembodiment indicates that the starboard cambered foil assembly 31 mayinclude a main cantilevered, flexible cambered metal foil 40, a rubbershock pad 41 to reduce shock and fatigue of the metal foil 40,reinforcing material 42 in the starboard pontoon 24, a bolt plate 43,and a bolt and lock nut assembly 44. In addition, the foil assembly 31may include a channel 45, rubber shock pad 46, a lower cantileveredflexible cambered foil 47, rubber shock fence 48 for added directionalstability and seating of a second bolt and lock nut assembley 49. Thebolt assemblies 44, 49 allow the entire foil assembly or only the lowerfoil 47 and fence 48 to be easily removed for replacement and/or repair.The cambered foils 40 and 47 bend in torsion, and therefore may bereplaced with larger or smaller foils depending on individual hullrequirements for higher speed or rough water operation.

[0058]FIG. 5 shows a stem cambered foil 32 that can be raised or loweredby hydraulic or pneumatic rams 50. For example, when the boat istraveling at high speeds into surface winds, the density of the spray,pressure and lift is reduced under the forward and/or center tunnelcambered foils 28, 28A when the stem cambered foil 32 in the form of ahovercraft skirt is raised. When foil 32 is lowered, the density of thespray, pressure and lift is increased on the forward and or centertunnel foil 28, 28A and stem foils 32 and 33.

[0059] As shown in FIG. 6, stem foils 32 and 33 are attached to hullpontoons 22 and 24 with a gasket 51 held in place with a clamp 52 toprevent air escaping between the stem foil 32, center foil 28 and hullpontoon 22. Increasing hull lift by lowering stem foil 32 reduces shockwhen traveling into the wind in rough water, accordingly demonstratingan increased wave frequency and profile. The design of the stem foilpresent invention tends to prevent the foil from being lifted above thesurface of the water and the propellers from cavitating duringoperation.

[0060]FIG. 7 shows an alternate design with the forward end of thecambered stern foil 32 in the tunnel, with gasket 51 preventing thespray from escaping between the fixed center tunnel cambered foil 28,stem cambered foil 32 and the sides of the tunnel. FIG. 8 shows a sternbracket 50A that can be adjusted upwardly and downwardly to raise orlower the stem cambered foil 32 and the center cambered tunnel foil 28.The trim angle of the cambered stern foil can also be adjusted with thepresent invention. Gasket 51 prevents spray from escaping between theadjustable center cambered tunnel foil 28 and the adjustable sterncambered foil 32. Gasket 51A prevents the spray from escaping betweenthe fixed forward cambered tunnel foil 28A and the adjustable centercambered tunnel foil 28.

[0061]FIG. 9 is a rear elevation view of a twin tunnel hull constructionhaving a single rear engine according to an embodiment of the presentinvention. FIG. 10 is a rear elevation view of a twin tunnel hullconstruction having a duel rear engine according to an embodiment of thepresent invention. FIG. 11 is a rear elevation view of a modified twintunnel construction having a single rear engine according to anembodiment of the present invention. FIG. 12 is a rear elevation view ofa hull having a single tunnel with twin engines according to anembodiment of the present invention. FIG. 13 is a partial, sideelevation view, partially in phantom of the catamaran hull of FIG. 1having pairs of bow, forward and center tunnel, and stern cambered foilsaccording to an embodiment of the present invention.

[0062]FIG. 9 shows rear cambered foils 32 and 33 and center camberedtunnel foils 28 mounted on a twin tunnel hull 20 powered by a singleengine 39. FIG. 10 shows foils 32, 33 and 28 mounted on a twin tunnelhull 20 powered by two engines 38, 39, and FIG. 12 shows a single stemfoil 32 and single center tunnel foil 28 mounted on a single tunnel hull20 having two engines 38, 39. FIG. 11 shows foil 32, 33 and 28 mountedon a twin tunnel hull with a single engine and relatively larger tunnels26.

[0063]FIG. 14 is a fragmentary sectional view showing the fitting ofcambered foils adjacent the bow, forward in the tunnel, aft in thetunnel and at the stern in a position intersecting the tunnel accordingto an embodiment of the present invention. FIG. 15 is a longitudinalsectional view of the boat hull of the present invention shown in FIG.13 underway at relatively low speeds. FIG. 16 is a longitudinalsectional view showing the boat hull of the present invention shown inFIG. 13 underway at high speed with a stern foil closed so as tocompress the dense spray within a tunnel. FIG. 17 is the rear elevationview of the boat shown in FIG. 16. FIG. 18 is a schematic exploded viewof the boat shown in FIGS. 13, 15 and 16, and having the pairs of bowfoils, forward tunnel foils, center tunnel foils and stem foils. Theturbulence and dense spray created by the bow foils and the compressionof this turbulence in the tunnels and by the tunnel foils and sternfoils enclosing the tunnels, is illustrated by increasing bubble densityat the after end of the flow stream. FIG. 19 is a fragmentary sideelevation view of a flexible cambered bow foil according to anembodiment of the present invention. FIG. 20 is a bottom plan view ofthe cambered foil shown in FIG. 19.

[0064] As illustrated in FIGS. 13 to 16, the bow cambered foils 30, 31,the air tight tunnel forward and center cambered foils 28,28A and airtight stem cambered foils 32, 33 cooperate with the tunnel 26 to providelift to the hull generated by water and dense spray. The water and airgenerated in part by the bow foils 30, 31 combine to form the densespray that provides pressure that gives lift to the cambered foils.Pressure data was obtained from during sea trials by using pitot tubesto determine the pressure on the different cambered bow 30,31, forwardand center tunnel 28, 28A, and stem foils 32, 33. Lift and drag of thedifferent foils, appendages and hull were calculated by regressionformulae on a computer relating pressure to spray density, speed, heightabove water, angle of attack, length, beam, camber and lift coefficient.Additional details of these trials and experimental results are providedin greater detail in the accompanying TABLES described hereinafter.

[0065] When the boat hull 20 is in the position shown in FIG. 16 whilebeing operated at high speed, dense spray and waves are compressed inthe rearward portion of the tunnel and stem foil, while directly andindirectly exerting an upward lifting force. The water and dense sprayat large velocity being compressed by the motion of the boat between thewalls of the tunnel(s) 26 in the rear and on the cambered tunnel foils28, 28A and air tight stem foils 32, 32 exert considerable lift.

[0066] In FIG. 19, the construction of a flexible cambered forward foil60 which is mounted upon a channel or I-beam 62, includes a camber andswept back configuration such that the foil passes over debris withoutdamage and bends under torsion so as to reduce fatigue stress/failurefrom bending. The leading edge 64 of the channel or I-beam 62 isinclined downwardly and aft so as to reduce drag and a shock pad 66 isfitted intermediate the channel or I-beam 62 and the hull exterior 74prior to fastening through bolts 68, 70 and 72. Similarly shock pad 80may be secured between channel or I-beam 62 and the cambered foil 60 bymeans of through holes 76, and 78.

V-Bottom Hull or Rigid Inflatable Hull Embodiment

[0067]FIG. 21 is a fragmentary end elevation view of an embodimenthaving a bow foil positioned on a V-bottom boat hull. FIG. 22 is aschematic view of shims or hydraulic means to adjust the angle of attack(x) of a cambered bow foil according to the present invention. FIG. 23is a side elevation view of a twin tunnel hull having bow camberedfoils, forward tunnel cambered foils, center tunnel cambered foils and apair of stem cambered foils according to an embodiment of the presentinvention. FIG. 24 is a plan view of the hull shown in FIG. 23. FIG. 25is a side elevation view of a V-bottom or rigid inflatable hull modifiedwith a chine aerofoil skirt to define axial tunnels influenced by thecambered bow foils, cambered center tunnel foils and cambered adjustablestem foils. FIG. 26 is a rear elevation view of the V-bottom hull shownin FIG. 25. FIG. 27 is a plan view of the V-bottom hull shown in FIG.25. FIG. 28 is a partial, side elevation view of the V-bottom hull shownin FIG. 25, demonstrating compression of tunnel turbulence and densespray by stern foils. FIG. 29 is a rear view of the boat hull shown inFIG. 23. FIG. 30 is a side view according to an embodiment of thepresent invention.

[0068]FIG. 21 shows the placement of forward cambered foil 86 on aV-bottom hull 82 with channel or I-beam 84, and includes an angle fence88. FIG. 22 is a schematic side view designating the angle of attack (x)of the bow cambered foil which may be adjusted by means of rubber shimsor hydraulic controls (not illustrated). FIGS. 23, 24 and 29 detail asingle tunnel 96 construction, having bow mounted cambered foils 94, aforward tunnel cambered foil 28A, a center tunnel cambered foil 28 andstem cambered foils 102,104 hydraulically actuated by struts 106, 108.

[0069] Rigid hovercraft type airtight skirts 98, 100 may also beemployed to enclose the transom end of the tunnel. As illustrated inFIGS. 25-29, in addition to the forward cambered foils 122 mountedbeneath the V-bottom hull or rigid inflatable hull 110, it is possibleto obtain even greater lift and stability from dense spray and pressureby the use of wing-like, longitudinal chine or bottom mounted air tightaerofoils 112 mounted between the chine or bottom and skeg of the hullfrom mid section to the stem to generate two tunnels to generate liftfrom the already described cambered foils.

[0070] As in the above-described construction the center tunnel camberedfoil 119 may be adjustable and the stem cambered foil 118 may beactuated by hydraulic cylinder 116. Experimental testing of variousaspects of the present invention indicate that unique and highlybeneficial results are obtained by the aforementioned embodiments andvariations thereof.

[0071] The following appendices are additionally provided and showvarious experimental results, test data and operational performance dataaccording to various embodiments of the present invention. The detailsof which will be described in detail hereinafter. TABLE I Method forCalculating Performance Three flexable cambered tunnel foils and twoflexable cambered bow foils Cambered tunnel foils Cambered Stern CenterFwd bow foils Hulls Prop Total A Design Number 1 1 1 2 Length ft 3 5 2.73 7.6 Beam aft 2 2 2 2 2.9 Aspect ratio B/L 0.67 0.4 0.74 0.67 CamberCld 0.1 0.1 0.1 0.1 Trim vs WL deg 3 3 8 3 3 Spray flo 3 3 8 Wettedvert(9) 3 5.4 46.8 3 Weight(4) 10000# Power 2.200 hp Yamaha 400 hp@ 5500rpm Propulsive 400 × .6 = 240 hp 240 horse power B Performance @ 45 kClb(1) 0.121 0.137 0.115 0.1 Lift/drag(1) 10.2/1 9/1 9.6/1 10/1 8.84/1(b) Velocity 45 k- 76.01 f/s Pressure (2) 3508 3549 213 5742 5742 Lift(3) Initial 1698 1944 98 4594 6084 14418 Revised 1698 1944 98 2584 36709994 Drag (3) Horizontal 166 213 10 258 117 764 (10) Vertical 12 25 2 848 95 Residual 321 321 178 238 12 266 486 1180 Lift required 10000/9994= 1.0006 1698 1944 98 2590 3670 10000 Drag 178 238 12 266 486 1180Appendage (12) 94 Wind (13) 437 1711 10000# Craft weight With foils Nofoils Speed mph  51.8  41 Propulsive HP required = velocity f/s ×  236hp 240 drag/550 = 76.01 × 1711/550 = Propulsive HP available = 2.200 HP 240 hp 240 Yamaha = 400 × 6 propulsive eff = Rpm to produce 236 hp =(236/240) × 5500 = 5408 5500 

[0072] TABLE II Hull/Performance Data Foil System (1) Clb and Lift/dragCambered planes Stern USN report 3147 Page 20 AR = 67 Spray flow = 3deg. Cld = 1 Clb = 121 Page 15 AR = 67 Spray flow = 3 deg. Clb = 121Lift/drag = 10.2/1 Center ″ ″ Page 20 AR = 4 Spray flow = 3 deg Cld = 1.Clb = 137 ″ ″ Page 3 AR = .4 Spray flow = 3 deg Clb = 137.Lift/drag = 9/Fwd Page 20 AR = .74 Spray flow = 3 deg. Cld = 1 Clb = 115 Page 3 AR =.74 Spray flow = 3 deg Clb = .115. L/D = 9.6/1 Bow foils ″ ″ Page 20 AR= .67 Water flow = 3 deg. Cld = .1 Clb = 121 @ 0 deg rise ″ ″ Clb = 10 @11 degree rise Page 15 Lift/drag = 10/1 45 k (2) Pressure Stern plane3508 Center plane 3549 Fwd plane  213 Bow foils 5742 Hulls 5742 (3) Liftand drag   45 k Hulls a = Trim 3 deg × exp1 1 = 3.35 Y = Length/beam =7.6/2.9 = 2.62. V = 76.01 f/s g = 32.2 cv = V/(gB) exp. 5 = 7.86. Cdl =[a exp 1.1(.012y exp.5 + .0095y exp2/cv exp2)] = 3.35(.0194 +.065/61.77) = 3.35(.0209) = .070 0 deg foil rise Cdl = .9 × 07 = .063Lift = Cdlx pitot pressure × B × B × 2 = 063 × 5742 × 2.9 × 2.9 × 2 =6084 45 k Stern plane Lift = Clb × press × B × B .121 × 3508 × 2 × 2 =1698 Drag = L/(L/D) 1698/10.2 = 166 Center plane Lift = Clb × press × B× B .137 × 3549 × 2 × 2 = 1944 Drag = L/(L/D) 1944/9.1 = 213 Fwdplane(8) Lift = Clb × press × B × B .115 × 213 × 2 × 2 = 98 Drag =L/(L/D) 98/9.6 = 102 Bow Foils Lift = Clb × press × B × B .1 × 5742 × 2× 2 × 2 = 4594 Drag = L/(L/D) 4594/10 = 459 (4) Weight Boat 4100#,engine & steering 1000#, foil system 500#, fuel 2500# 500 gal, crew 400#& Misc 500# = Total weight 9000# + 1000# additional fuel and misc =10000# (5) Stern cambered plane(foil) 45 k (a) Trim deg 1 Stern plane vscenter plane 3 2 Center plane vs WL 3 3 Stern plane vs WL 6 4 Sternplane water flow 3 (b) Height 1 Stern plane pitot aft vs WL 0.15 2 Sternplane aft vs WL. Ht + .13 0.28

[0073] TABLE III Hull/Performance Data Foil System 45 k (5) Sterncambered plane(foil) 3 Stern plane fwd a Sin trim × 3   sin 6 × 3 0.314b 1698 × length × Cld = 1698 × 3 × 1 = 0.051 c.Stern plane aft 0.280.645 4 Stern plane pitot fwd vs WL. Ht − .17 0.48 (c) Pressure   .5 ×density × f/s × f/s 1 Stern plane aft pitot 2 Stern plane fwd pitot 3Stern plane ave pitot 3508 (d) Stern plane camber Length 3 ft x =   .1.2 .3 .4 .5 .6 .7 .8 .9 1. x =  .3 .6 .9 1.2 1.5 1.8 2.1 2.4 2.7 3. y =−.0001 .001 .003 .006 .010 .013 .011 .003 −.017 −.051 (6) Centercambered planet (foil) (a) Trim   deg 1 Center plane vs fwd plane 0 2Center plane vs WL 3 3 Center plane vs Spray flow 3 (b) Height 1 Centerplane pitot aft vs WL 0.48 2 Center plane aft vs WL. Ht + .13 0.61 3Center plane fwd a. Sin trim × 5 0.262 b. 1698 × length × Cld = .1698 ×5 × 1 = 0.085 c. Center plane aft 0.61 0.96 4 Center plane pitot fwd−.17 0.79 5 Center plane pitot ave ht. 0.64 (c) Pressure   .5 × density× f/s × f/s 1 Center plane aft pitot 2 Center plane fwd pitot 3 Centerplane ave 3549 (d) Center plane camber Length 60″ x =  .1 2 3 4 .5 6 7 8 9 1 x =  6 12 18 24 30 36 42 48 54 60 y = 00−.02 −.06 −12 −.2 −26 −.22 −05 34 1 02 (7) Fwd cambered plane(foil) (a)Trim  deg 1 Fwd plane vs WL 8 2 Fwd plane vs Spray flow 8

[0074] TABLE IV Hull/Performance Data Foil System 45 k (7) Fwd camberedplane(foil) (b) Height 1 Fwd plane pitot aft vs WL 0.64 2 Fwd plane aftvs WL. Ht + 13 0.77 3 Fwd plane fwd a. Sin trim × (2 deg) 0.105 b 1698 ×length × Cld = 1698 × 3 × 1 = 0.051 c Fwd plane aft 0.77 1.87 4 Fwdplane pitot fwd − 17 1.7 5 Fwd plane pitot ave ht 1.58 (c) Pressure   5× density × f/s × f/s 1 Fwd plane aft pitot 392 2 Fwd plane fwd pitot 73 Fwd plane ave 215 (d) Center plane camber Length 32 4″ x =     1 2 3 45 6 7 8 9 10 x =      0 3.6 7.2 10.8 14.4 18 21.6 25.2 28.8 32.2 y = 0−.01 −.04 −.07 −.12 −.16 −.12 −.04 .2 .61 (8)Bow Foils (a) Trim fwdfoils vs WL   3 deg (b) Pressure 5742 Bow foil camber Length 3 ft x =   .1 .2 .3 4 .5 .6 .7 .8 .9 1. x =  .3 .6 .9 1.2 1.5 1.8 2.1 2.4 2.7 3. y =−.0001 .001 .003 .006 .010 .013 .011 .003 −.017 −051 A 45 k Camberedplanes Bow (9) Wetted surface Stern Center Fwd Foils Hulls TotalHorizontal Water Width ave 2.9 Length 7.6 Number 2 Area 44.1 44.1Vertical Water Height ave 0.25 0.15 0.6 Length 3 2 7.6 Number 2 4 4 Area1.5 1.2 18 24.7 Spray Height ave 0.25 6 1.8 Length 3 5 2.7 Number 2 2 2Area 1.5 6 9.7 17.2

[0075] TABLE V Hull/Performance Data Foil System 45 k (10) Vertical dragA 45k (a) Cf Schoenherr @ Reynolds no 76 01 f/s Reynolds no = velocityx(length/viscosity) Length = 26.25. Viscosity = @ 50 deg salt = 1.46 × 10exp −5 Reynolds no = 76.01 × 26.25/1.46 × 10 exp −5 1 366 × 10 exp +8 Cf@Rey no = 1 366−(1 .366 − 1 060) × 12/ 2 = 1 182 × 10 exp −3 (b) Pitotpressure Lift 10000 Water .5 × 64/32.2 × 76 01 × 76.0 1 = 5742 Spray-Stern plane 3508 Center plane 3549 Fwd plane .213 (c) Frictionalresistance. Cf × press × area Stern plane Water 1 182 × 10 exp −3 × 1.5× 3805 6.1 Spray 1.182 × 10 exp −3 × 1.5 × 3805 6.1 Center plane Spray1.182 × 10 exp −3 × 6 × 3549 25.2 Fwd plane Spray 1.182 × 10 exp −3 ×9.7 × 213 2.4 Fwd Foils Water 1.182 × 10 exp −3 × 1.2 × 5742 8.1 HullsWater Hor 1.182 × 10 exp −3 × 44.1 × 5742 299 Vert 1.182 × 10 exp −3 ×181 × 5742 121 (d) Residual resistance-Tan Trimx Lift-Horizontal onlyHulls 3670 × tan 5 deg = 3670 × .0875 321 (e) Hull lift/drag3670/Resistance friction & residual 3670/(299 + 321) = 5.91 (11)Propeller (12) Appendage resistance (a) normal .04 × frictional andresidual resistance = Drag 1181 Appendage resistance @8% 94 (13) Windresisrtance (a) Cwx 5x 0024xvxvxArea Cw. = 1.28. Area = 6 2 × 2 + 8.3 ×2.75 + 4 × 35 = 49.250 1.28 × 49.3 × .5x 0024 × 76 01 × 76.01 = 437

[0076] TABLE VI Hull/Performance Data Foil System 45 k Revised (3) Liftand drag Hulls a = Trim 3 deg × exp1 .1 = 3 35 Y = Length/beam = 3/2.9 =1.03. V = 76 01f/s g = 32 2 cv = V/(gB) exp.5 = 7.86 Cdl = [a exp 11(.012y exp.5 + .0095y exp2/cv exp2)] = 3.35(.0121 + .010/61.77) = 335(.0121 + 0006) = .042. 0 deg foil rise Cdl = 9 × 042 = .038 Lift =Cdlx pitot pressure × B × B × 2 = 038 × 5742 × 2 9 × 2.9 × 2 = 3670 (9)Wetted surface A 45 k Hulls Horizontal Water (c) Frictional resistanceCf × press × area Width ave 2 9 Hulls Length 3 Water Hor 1.182 × 10 exp−3 × 17 4 × 5742 117 Number 2 Vert 1 182 × 10 exp −3 × 7 2 × 5742 48Area 174 Vertical Water Height ave 06 Length 3 Number 4 Area 72 (3) Liftand drag Bow Foils Lift = =2584 Drag = L/(L/D) 2584/10 = 258 (d)Residual resistance-Tan Trimx Lift-Horizontal only Hulls Residual 3670tan 5 deg 321 Frict horizontal 117 vertical 48 486

[0077] A method for calculating the enhanced performance of thepreferred embodiments is indicative of the highly desirable features ofthe present invention. The method for calculating the amount ofenhancement of performance from modifying the boat with cambered bow,forward and/or center tunnel and stem foils, includes the steps of:

[0078] Defining before modification the boat height above waterline,wetted surface, trim angle, drag, weight, horse power and revolutionsper minute vs speed. TABLE III shows cambered foils for calculating theenhanced performance from sea trials of a catamaran 26.5 feet in lengthwith weight of 10000 pounds and 400 rated hp requires 5500 rpm to reach41 mph;

[0079] Defining modifications: the dimensions of the bow, forwardtunnel, center tunnel and stem cambered foils; length, beam, aspectratio, camber coefficient, trim angle of water flow, degrees of floorrise and weight. Specific dimensions are shown in the accompanyingTABLES, particulary the specifications of the bow, stem, center andforward cambered foils;

[0080] Defining foil lift: based on lift coefficient, pressure and foilbeam. Lift coefficient is estimated from aspect ratio, cambercoefficient and trim angle of water flow and was obtained from a US Navyreport “Graphs For Designing Cambered Planing Surfaces.” Pressure isbased on cambered foil speed vs height above water obtained fromregression calculations from sea trial data of prototype cambered foils,showing (1) Clb and Lift/drag; (3) Lift and drag; (5) Stern foil trim,height, pressure and camber; (6) Center foil trim, height, pressure andcamber; (7) Forward foil trim, height, pressure and camber. (8) Bow foiltrim, height, pressure and camber; (9) Wetted surface; (10) Verticaldrag; (12) Appendage resistance; (13) Wind resistance; (3) Lift anddrag; and (9) Wetted surface. Revisions are required to have lift equalto craft weight of 10000 lbs;

[0081] Defining foil drag: based on foil lift/(lift/drag ratio). Lift/drag ratio was obtained from US Navy report 3147 and was based onaspect ratio, lift coefficient and trim angle of water. Vertical dragwas estimated from vertical wetted surface times coefficient offriction. Drag, (9) wetted surface and revised drag of 1711 lbs;

[0082] Defining after modification hull lift: based on lift coefficient,pressure and beam (3) shows hull lift and (2) shows pressure;

[0083] Defining after modification hull drag including: based anfrictional resistance, reduced hull wetted surface, coefficient offriction, residual hull resistance, wind and appendage resistance. Thedata shows revised hull drag and wetted surface; (10) frictionalresistance, (12) appendage resistance and (13) wind resistance;

[0084] Defining speed vs. horsepower before and after modification withcambered foils: based on speed equal to propulsive horsepower ×550divided by foil and hull drag where propulsive hp equals 0.6 times ratedhorsepower times required divided by rated rpm. Performance shows 400rated hp requires 5408 rpm to achieve 51.8 mph; and

[0085] Defining the amount of enhanced performance: based on the abovemethod of calculation indicates a 26.6 ft catamaran with 400 horsepowerhad a speed of 41 mph before modification compared to 51.8 mph aftermodification with cambered foils, an increase of 26%.

[0086] Enhanced performance of the preferred embodiments during seatrials of a 23 ft prototype with 275 hp at 82% of rated rpm in smoothwater showed the bow and stem foils generated lift of 58% of craftweight of 4048 lbs (including passengers and fuel, raised hull, reducedwetted surface and increased hull speed of 9.2% to 45 knots). In roughwater to reduce pitching and the risk of flipping at high speeds goinginto rough waves the bow height and lowering the stern foils reducedtrim. This increases the stern foil lift and reduces the angle of attackon the bow foils that reduces the bow lift and generates bow down sternlift.

[0087] Increasing the angle of attack (x) of the propeller shaft alsoreduces the angle of attack on the bow foils and which reduces bow liftand height. The bow height and trim was increased by lowering thepropeller shaft angle to raise the stern foils to prevent the bow fromdiving in a following, rough sea. Trials were conducted in waves heightof 3.7 ft and winds of 55 knots. The 23 foot prototype at 3000 of rated5500 rpm speed without foils in a head sea was 10 k or less. Theaddition of the bow and stern foils increased the speed to 22 knotsreduced the pitch to 63% or 17 degrees and vertical acceleration gloading to 58% or 5g. The foil system increased the moment of inertia byover 5 times. Increased moment of inertia reduces pitching, verticalaccelerations and wave shock and improved top speed, stability andcomfort in rough water.

[0088] The method for calculating the amount of enhancement ofperformance from modifying different boats with cambered bow, tunnel andstern foils indicated increased speed, lift/drag ratios and efficiencywith reduced propulsive power. This method for calculating performanceindicated a US Navy 23 foot test craft required 134.4 propulsive hpwithout foils at 40.7 knots and 135.5 propulsive hp with foils at 44.5knots compared to actual propulsive hp of 135 in actual sea trials.

[0089] Dense spray generated by the cambered bow foils flowing thru therigid airtight adjustable cambered stern foils dampens pitch andvertical accelerations in a rough sea. The method for calculatingenhanced performance was based on sea trials in smooth and rough water.Trial data was obtained on: density of tunnel spray, speed, pitch, rolland vertical acceleration vs. engine rpm, power, weight and wave heightfrom a 23 ft prototype with 275 horsepower with and without camberedfoils. Calculating methods were developed based on this and other datato estimate lift and resistance from the hulls, bow, tunnel and sterncambered foils at different engine rpm and power. This method ofcalculation accurately predicted lift, resistance and speed vs power forthe prototype with and without foils installed.

[0090] The lift/resistance ratio was 29% higher with the foils installedthan without the foils installed. The U.S. Navy tested the prototype andrecommended “the foil system as tested appears to improve craftperformance in a seaway.” “The foil system prevents the bow from divingin following seas or pitching in a head sea; reduces the g-loading in aBeam sea; and finally, increases the craft speed at the top end. Werecommended that the foil system concept be considered for applicationand evaluation of future U.S. Navy hulls.”

[0091] The invention being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A boat hull comprising: a bow and a stern; awaterline extending between said bow and said stern; at least one tunnelextending axially in a direction from said bow toward said stern andhaving a forward end, a center region and an aft end; a pair of flexiblecambered foils, said flexible cambered foils supported on sides of saidbow beneath the water line, said flexible cambered foils being capableof controlling a flow within said at least one tunnel and creating adense spray in an end of said tunnel while cushioning shock and liftingsaid bow; and at least one fixed, cambered foil at the after or theforward end of said at least one tunnel generating lift from a pressurebeing generated by the dense spray within said at least one tunnel. 2.The boat hull according to claim 1, further comprising at least onecambered foil at the after end and at least one cambered foil at theforward end of said at least one tunnel generating lift from a pressurebeing generated by the dense spray within said at least one tunnel. 3.The boat hull according to claim 1, said boat hull further comprising av-bottom or rigid inflatable hull.
 4. The boat hull according to claim1, said boat hull further comprising a catamaran hull.
 5. The boat hullaccording to claim 1, further comprising a rigid cambered stem foilforming a skirt extending substantially across the tunnel andperipherally enclosing a transom of said stem, said stem foil beingcapable of preventing air from escaping, compressing said dense sprayand thereby lifting said stem.
 6. The boat hull according to claim 5,further comprising a center tunnel cambered foil at said forward endbeing fixed or variable in height, said stem cambered stem foil beingvariable in height and or in trim so as to control the lift of saidhull.
 7. A boat hull comprising: a bow and a stem, said stem including atransom; a waterline extending between said bow and said stem; a pair oftunnels extending axially in a direction from said bow toward said sternand having a forward end, a center region and an aft end; a pair offlexible cambered foils, said flexible cambered foils supported on sidesof said bow beneath the water line, said flexible cambered foils beingcapable of controlling a flow within said at least one tunnel andcreating a dense spray in an end of said tunnel while cushioning shockand lifting said bow; and at least one pair of cambered tunnel foils atthe aft or forward ends of said tunnels, respectively, wherein each ofsaid tunnels includes a respective tunnel foil generating lift from apressure being generated by the dense spray within said at least onetunnel.
 8. The boat hull according to claim 7, wherein said tunnel foilsare positioned at said forward ends of said tunnels.
 9. The boat hullaccording to claim 7, wherein said tunnel foils are positioned at saidcenter section of said tunnels.
 10. The boat hull according to claim 7,further comprising a pair of cambered stern foils forming a skirtextending substantially across said tunnels so as to peripherallyenclose said transom and prevent air from escaping, compressing saiddense spray and lifting thereby said stern.
 11. The boat hull accordingto claim 8, further comprising a pair of cambered stern foils forming askirt extending substantially across said tunnels so as to peripherallyenclose said transom and prevent air from escaping, compressing saiddense spray and lifting thereby said stern.
 12. The boat hull accordingto claim 9, further comprising a pair of cambered stem foils forming askirt extending substantially across said tunnels so as to peripherallyenclose said transom and prevent air from escaping, compressing saiddense spray and lifting thereby said stem.
 13. The boat hull accordingto claim 7, said boat hull further comprising a v-bottom or rigidinflatable hull.
 14. The boat hull according to claim 7, said boat hullfurther comprising a catamaran hull.
 15. The boat hull according toclaim 1, wherein at least one of said foils includes a foil assembly,said foil assembly including a main cantilevered, flexible camberedmetal foil, a rubber shock pad, reinforcing material, a bolt plate, anda bolt and lock nut assembly.
 16. A method of modifying the powered boathull claimed in claim 1 to obtain enhanced lift, performance and roughwater stability with said cambered foils, said method comprising thesteps of: (a) defining a boat height above a waterline, a wetted surfacearea, a trim angle, a hull weight and a horse power vs. speedrequirement; (b) defining dimensions of the cambered foils and hull,said dimensions including length, beam, camber, trim, floor rise andweight; (c) defining foil lift and drag based on said cambered foildimensions, trim, spray density, speed, height above waterline, wettedsurface area, coefficient of friction and sea trial data from prototypecambered foils; (d) modifying a hull with a hull modification toincorporate said cambered foils; (e) defining hull lift and drag aft thehull modification based on water pressure, beam, length, trim, velocity,gravity, coefficient of friction, floor rise, wetted surface, residualhull resistance, appendage and wind resistance; (f) defining the speedvs. horsepower before and aft said hull modification with camberedfoils; and (g) calculating enhanced performance.